1207. Vaccinia Virus Infection Acquired from an Occupational Needlestick—San Diego, California, 2019

Background Vaccinia virus, a virus similar to but less virulent than variola virus, is a component of smallpox vaccines and increasingly used for medical research. Vaccinia immunoglobulin intravenous (VIGIV) and tecovirimat are stockpiled in the U.S. Strategic National Stockpile (SNS) for potential smallpox bioterror events, but only VIGIV is licensed for vaccinia treatment. On January 12, 2019, CDC was consulted for worsening infection in a laboratory worker after a needlestick with vaccinia. Methods We investigated demographic, clinical, vaccination, and exposure history and determined likelihood of vaccinia virus infection. Identity of the specific strain was sought because some have genetic modifications that might impact virulence. Discussions among stakeholders informed treatment decisions and facilitated medication access and usage. Swabs from the lesion were tested by real-time polymerase chain reaction for orthopoxvirus DNA, which includes vaccinia. Results The affected worker was an otherwise healthy 26-year-old woman who developed a pustular lesion at the needlestick site on her left index finger (Image). The patient had been injecting vaccinia virus into a mouse and had declined nationally recommended vaccination. Edema, lymphadenopathy, and fever raised concern for severe illness; neither the patient nor occupational health were certain of the vaccinia strain type. CDC, SNS, local health departments, drug manufacturers, and clinicians rapidly collaborated to make treatment decisions based on available information and ensure delivery of both biologics and administration of tecovirimat under an expanded access investigational new drug protocol. Eventually, a wound swab tested positive and the strain was determined to be one with no known impact on virulence. Conclusion With increasing use of vaccinia in research, occupational infections may continue to occur. Health clinics should extensively counsel staff who decline vaccination and have documentation on-hand about vaccinia virus types to inform treatment decisions. This response prompted CDC to develop outreach materials specifically for occupational vaccinia exposures. Disclosures All authors: No reported disclosures.

A Genome-Wide Haploid Genetic Screen Identifies Heparan Sulfate-Associated Genes and the Macropinocytosis Modulator TMED10 as Factors Supporting Vaccinia Virus Infection

ABSTRACTVaccinia virus is a promising viral vaccine and gene delivery candidate and has historically been used as a model to study poxvirus-host cell interactions. We employed a genome-wide insertional mutagenesis approach in human haploid cells to identify host factors crucial for vaccinia virus infection. A library of mutagenized HAP1 cells was exposed to modified vaccinia virus Ankara (MVA). Deep-sequencing analysis of virus-resistant cells identified host factors involved in heparan sulfate synthesis, Golgi organization, and vesicular protein trafficking. We validated EXT1, TM9SF2, and TMED10 (TMP21/p23/p24δ) as important host factors for vaccinia virus infection. The critical roles of EXT1 in heparan sulfate synthesis and vaccinia virus infection were confirmed. TM9SF2 was validated as a player mediating heparan sulfate expression, explaining its contribution to vaccinia virus infection. In addition, TMED10 was found to be crucial for virus-induced plasma membrane blebbing and phosphatidylserine-induced macropinocytosis, presumably by regulating the cell surface expression of the TAM receptor Axl.IMPORTANCEPoxviruses are large DNA viruses that can infect a wide range of host species. A number of these viruses are clinically important to humans, including variola virus (smallpox) and vaccinia virus. Since the eradication of smallpox, zoonotic infections with monkeypox virus and cowpox virus are emerging. Additionally, poxviruses can be engineered to specifically target cancer cells and are used as a vaccine vector against tuberculosis, influenza, and coronaviruses. Poxviruses rely on host factors for most stages of their life cycle, including attachment to the cell and entry. These host factors are crucial for virus infectivity and host cell tropism. We used a genome-wide knockout library of host cells to identify host factors necessary for vaccinia virus infection. We confirm a dominant role for heparin sulfate in mediating virus attachment. Additionally, we show that TMED10, previously not implicated in virus infections, facilitates virus uptake by modulating the cellular response to phosphatidylserine.

A genome-wide haploid genetic screen for essential factors in vaccinia virus infection identifies TMED10 as regulator of macropinocytosis

Vaccinia virus is a promising viral vaccine and gene delivery candidate, and has historically been used as a model to study poxvirus-host cell interactions. We employed a genome-wide insertional mutagenesis approach in human haploid cells to identify host factors crucial for vaccinia virus infection. A library of mutagenized HAP1 cells was exposed to Modified Vaccinia Virus Ankara (MVA). Deep-sequencing analysis of virus-resistant cells identified host factors involved in heparan sulfate synthesis, Golgi organization, and vesicular protein trafficking. We validated EXT1, TM9SF2 and TMED10 TMP21/p23/p24δ) as important host factors for vaccinia virus infection. The critical role of EXT1 in heparan sulfate synthesis and vaccinia virus infection was confirmed. TM9SF2 was validated as a player mediating heparan sulfate expression, explaining its contribution to vaccinia virus infection. In addition, TMED10 was found to be crucial for virus-induced plasma membrane blebbing and phosphatidylserine-induced macropinocytosis, suggesting that TMED10 regulates actin cytoskeleton remodelling necessary for virus infection.